Nokea
Which of the following bacteria is known for causing the disease tetanus?
- A. Clostridium tetani
- B. Clostridium perfringens
- C. Streptococcus pyogenes
- D. Escherichia coli
Correct Answer: A
Rationale: The correct answer is A: Clostridium tetani. This bacterium is known for causing tetanus due to its ability to produce tetanospasmin, a neurotoxin that leads to the characteristic muscle stiffness and spasms seen in tetanus. Clostridium perfringens (Choice B) is associated with gas gangrene, Streptococcus pyogenes (Choice C) causes streptococcal infections, and Escherichia coli (Choice D) is known for causing various gastrointestinal infections. Therefore, Choices B, C, and D are incorrect as they are not the causative agents of tetanus.
You may also like to solve these questions
What reaction is catalyzed by a beta-lactamase enzyme
- A. the final cross-linking reaction to form the bacterial cell wall
- B. the biosynthesis of the penicillin structure from the amino acid valine and cysteine
- C. the hydrolysis of the four-membered ring present in penicillin
- D. the hydrolysis of the acyl side chain from penicillin structures
Correct Answer: C
Rationale: The correct answer is C: the hydrolysis of the four-membered ring present in penicillin. Beta-lactamase enzyme catalyzes the hydrolysis of the four-membered beta-lactam ring present in penicillin, rendering the antibiotic ineffective against bacterial cell walls. This enzyme breaks the bond in the beta-lactam ring, thus inactivating the antibiotic.
Incorrect choices:
A: the final cross-linking reaction to form the bacterial cell wall - This is incorrect as beta-lactamase does not participate in the formation of bacterial cell walls.
B: the biosynthesis of the penicillin structure from the amino acid valine and cysteine - This is incorrect as beta-lactamase is not involved in the biosynthesis of penicillin.
D: the hydrolysis of the acyl side chain from penicillin structures - This is incorrect as beta-lactamase specifically targets the beta-lactam ring, not the
A 25-year-old patient reports pain, burning at urination and scarce secretion in the morning. Urine samples are taken and cultivated on blood and MacConkey agar. After 24 hours of incubation, the culture are sterile. Which one of the following bacteria is the most probable cause of this disease?
- A. Escherichia coli
- B. Chlamydia trachomatis
- C. Streptococcus pneumoniae
- D. Neisseria gonorrhoeae
Correct Answer: B
Rationale: The correct answer is B: Chlamydia trachomatis. This is because Chlamydia trachomatis is an obligate intracellular bacterium that cannot be cultured on standard agar plates. The symptoms described by the patient, such as pain, burning at urination, and scarce secretion in the morning, are indicative of a possible chlamydial infection. Additionally, the fact that the urine cultures are sterile after 24 hours of incubation suggests that the causative agent is not a typical bacteria like Escherichia coli, Streptococcus pneumoniae, or Neisseria gonorrhoeae, which would normally grow on agar plates. Therefore, Chlamydia trachomatis is the most probable cause of this disease.
Summary:
A: Escherichia coli - Incorrect, as it is a common cause of urinary tract infections and would typically grow on agar plates.
C: Streptococcus pneumoniae - Incorrect, as it is
A 45 year old male died from disseminated tuberculosis. On autopsy the symptoms of tuberculosis were confirmed by both microscopical and histological analyses. What kind of hypersensitivity reaction underlies the process of granuloma development?
- A. Delayed
- B. Antibody-dependent cytotoxicity
- C. Complement-dependent cytotoxicity
- D. Anaphylactic
Correct Answer: A
Rationale: The correct answer is A: Delayed hypersensitivity reaction. In granuloma development in tuberculosis, macrophages present antigen to T cells, leading to a delayed hypersensitivity reaction. This triggers the recruitment of more macrophages and formation of granulomas. Antibody-dependent cytotoxicity (B) and complement-dependent cytotoxicity (C) involve antibodies and complement proteins in immediate hypersensitivity reactions, which are not the primary mechanisms in tuberculosis. Anaphylactic reaction (D) is an acute systemic allergic reaction mediated by IgE antibodies, not relevant to granuloma formation in tuberculosis.
Growth of bacteria is a result of:
- A. Air consumption
- B. Water adsorption
- C. Enzyme production
- D. Radio isotopes
Correct Answer: B
Rationale: The growth of bacteria is a result of water adsorption because water is essential for various metabolic processes within the bacterial cells, such as nutrient uptake, energy production, and waste removal. Water serves as a medium for chemical reactions to occur and provides structural support to the bacteria. Without sufficient water, bacteria cannot thrive and reproduce.
A: Air consumption is incorrect because while bacteria may require oxygen for respiration, it is not the primary factor for their growth.
C: Enzyme production is incorrect because enzymes are important for various cellular functions but do not directly influence bacterial growth.
D: Radio isotopes are incorrect as they are not essential for bacterial growth and can even be harmful to bacterial cells.
For infections caused by coronaviruses is NOT true that;
- A. Most commonly associated with URT infections
- B. May be asymptomatic
- C. SARS is an atypical pneumonia that can be complicated with acute respiratory failure and can cause death
- D. Reinfections cannot be observed
Correct Answer: D
Rationale: Step-by-step rationale for why answer choice D is correct:
1. Coronaviruses can cause reinfections due to potential waning immunity.
2. Studies have shown cases of reinfections with different strains or within a short period.
3. This contradicts the notion that reinfections cannot be observed.
Summary:
A: Incorrect because some coronaviruses can cause lower respiratory tract infections.
B: Incorrect as coronaviruses can exhibit varied symptomatology including asymptomatic cases.
C: Incorrect as some coronaviruses like SARS can lead to severe pneumonia and complications.